ABSTRACT Enrollment in consumer-directed health plans (CDHPs) ? plans with high deductibles and tax-advantaged savings accounts ? is increasing rapidly. In 2015, 25% of workers with employer-sponsored health insurance were enrolled in CDHPs, and CDHPs are the dominant plan type offered through individual and small group Marketplace plans. When examining the effect of CDHPs on health conditions with both emergent and chronic components, determining the effect a priori can be difficult. Indeed, CDHPs have been shown to reduce health care spending in many contexts but minimal CDHP effects have been found when examining care with inelastic demand. Despite the high prevalence of substance use disorders (SUD) in the U.S., there is little published research analyzing the impact of CDHPs on those with SUD. Previous research on CDHPs suggests that vulnerable populations, including those with chronic health conditions, are at the greatest risk of making poor decisions in response to higher cost sharing. This evidence raises concerns about the potential effects of CDHPs for individuals with SUD since these conditions are most effectively managed as chronic conditions, often co-occur with mental illness and other chronic medical conditions, and can be costly. Furthermore, given that SUD is vastly under-treated and access to evidence-based SUD treatments (e.g., medication-assisted treatment) is severely limited in many communities, the shift toward CDHPs might be creating further barriers to SUD identification, treatment initiation and the continuity of care. Alternatively, CDHPs could drive more value-based health care decision-making, leading to increased use of evidence-based SUD treatments. Using customized commercial insurance data from the Truven Health MarketScan Database (2011-2018) with new claims-derived benefit design information, we propose to study how the shift toward CDHPs affects individuals with SUD. First, we will identify the demographic and care utilization characteristics of individuals with SUD choosing to enroll in CDHPs, and of those with SUD subsequently opting to disenroll from CDHPs (Aim 1). Second, we will compare the effects of the decision to offer a CDHP option to only offering traditional plan choices on SUD treatment utilization, including use of medication-assisted treatment (Aim 2). Third, we will compare the effects of the decision to offer a CDHP option to only offering traditional plan choices on treatment for diabetes, cardiovascular disease, depression and nicotine dependence among enrollees with and without a co-occurring SUD (Aim 3). The proposal's significance lies in our ability to produce new information on whether the movement toward enrollment in CDHPs is exacerbating under-treatment of SUD or driving greater use of value-based care. In the context of the opioid epidemic and broader clinical and societal challenges in connecting individuals with SUD with evidence-based care, it is critical to understand whether and how incentives in the insurance market encouraging enrollment in high deductible plans with savings accounts are affecting initiation of and continuation in evidence-based SUD treatment.